Interlayer for laminated glass, and laminated glass

ABSTRACT

An interlayer film for laminated glass that has a one-layer structure or a two or more layer-structure includes a first layer containing a thermoplastic resin, wherein the first layer has a glass transition temperature of 10° C. or lower, and wherein the interlayer film has an equivalent stiffness of 2.4 MPa or greater at 25° C.

TECHNICAL FIELD

The present invention relates to an interlayer film for laminated glassused for obtaining laminated glass. Furthermore, the present inventionrelates to laminated glass including the interlayer film for laminatedglass.

BACKGROUND ART

Laminated glass is excellently safe because it generates only a smallamount of scattering glass fragments even when being subjected toexternal impact and is broken. Therefore, laminated glass is widely usedin automobiles, railroad cars, airplanes, ships, buildings, and thelike. Laminated glass is manufactured by interposing an interlayer filmfor laminated glass between two glass plates.

Interlayer films for laminated glass include a single-layered interlayerfilm having a structure consisting of a single layer and a multilayeredinterlayer film having a structure consisting of two or more layers.

The following Patent Literature 1 discloses, as an example of aninterlayer film for laminated glass, a sound insulating layer containing100 parts by weight of a polyvinyl acetal resin having a degree ofacetalization of 60 to 85 mol %, 0.001 to 1.0 part by weight of at leastone kind of metal salt among alkali metal salts and alkaline earth metalsalts, and a plasticizer in an amount of greater than 30 parts byweight. This sound insulating layer alone can be used as an interlayerfilm.

The following Patent Literature 1 also describes a multilayeredinterlayer film in which the aforementioned sound insulating layer andanother layer are laminated. The other layer laminated on the soundinsulating layer contains 100 parts by weight of a polyvinyl acetalresin having a degree of acetalization of 60 to 85 mol %, 0.001 to 1.0part by weight of at least one kind of metal salt among alkali metalsalts and alkaline earth metal salts, and a plasticizer in an amount of30 parts by weight or less.

The following Patent Literature 2 discloses an interlayer film which isa polymer layer having a glass transition temperature of 33° C. orhigher. Patent Literature 2 describes that the polymer layer is disposedbetween glass plates having a thickness of 4.0 mm or less.

The following Patent Literature 3 discloses an interlayer filmcontaining (A) polyvinyl acetal, (B) at least one kind of plasticizer,(C) fumed silica, and (D) at least one kind of basic compound. In thisinterlayer film, a difference in refractive index between (C) fumedsilica and plasticized polyvinyl acetal (A+B) is 0.015 or less, and aweight ratio of C/(A+B) is 2.7/100 to 60/100.

CITATION LIST Patent Literature

[Patent Literature 1] JP-A-2007-070200

[Patent Literature 2] US 2013/0236711A1

[Patent Literature 3] WO 2008/122608A1

SUMMARY

Laminated glass including an interlayer film of the related art asdescribed in Patent Literature 1 to 3 has low bending rigidity in somecases. Therefore, for example, in a case where the laminated glass isused in side doors of an automobile, because there is no frame forfixing the laminated glass, and the laminated glass bends due to lowrigidity, it is difficult to open and close the glass in some cases.

In recent years, in order to lighten a laminated glass, the reduction ofa thickness of a glass plate has been required. In laminated glass inwhich an interlayer film is interposed between two glass plates, in acase where the glass plate has a small thickness, it is extremelydifficult to maintain bending rigidity at a sufficiently high level.

For example, even if the thickness of the glass plate is reduced, aslong as the bending rigidity of the laminated glass can be improved dueto the interlayer film, the laminated glass can be lightened. In a casewhere the laminated glass is light, an amount of materials used in thelaminated glass can be reduced, and an environmental load can bereduced. Furthermore, in a case where light laminated glass is used inautomobiles, fuel efficiency can be improved, and as a result, anenvironmental load can be reduced.

Patent Literature 3 describes the improvement of dynamic characteristicssuch as tensile strength. Generally, tensile strength is different frombending rigidity. In some cases, even if tensile strength can beimproved to some extent, bending rigidity cannot be sufficientlyimproved.

For laminated glass including an interlayer film, in addition to highbending rigidity, excellent sound insulating properties are required. InPatent Literature 3, even though tensile strength can be improved, soundinsulating properties cannot be sufficiently improved in some cases.Particularly, Patent Literature 3 does not state that, in a case whereglass plates having a small thickness are combined with an interlayerfilm including a sound insulating layer having a low glass transitiontemperature, bending rigidity of the laminated glass becomesinsufficient.

One or more embodiments of the present invention provide an interlayerfilm for laminated glass that can improve bending rigidity and soundinsulating properties of laminated glass. Furthermore, one or moreembodiments of the present invention provide laminated glass includingthe aforementioned interlayer film for laminated glass.

According to one or more embodiments of the present invention, there isprovided an interlayer film for laminated glass that has a one-layerstructure or a two or more-layer structure and includes a first layercontaining a thermoplastic resin, in which a glass transitiontemperature of the first layer is 10° C. or lower, and an equivalentstiffness of the interlayer film for laminated glass at 25° C. is 2.4.MPa or greater.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, a Young's modulusof the first layer at 25° C. is 0.4 MPa to 6 MPa.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, a glass transitiontemperature of the first layer is 5° C. or lower.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, the first layercontains silica particles.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, a content of thesilica particles in the first layer is 5 parts by weight to 64 parts byweight with respect to 100 parts by weight of the thermoplastic resin inthe first layer.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, the interlayer filmfurther includes a second layer containing a thermoplastic resin, inwhich the second layer is disposed on a first surface side of the firstlayer.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, a Young's modulusof the second layer at 25° C. is 3 MPa to 700 MPa.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, the thermoplasticresin in the first layer is a polyvinyl acetal resin, and thethermoplastic resin in the second layer is a polyvinyl acetal resin.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, a content ratio ofhydroxyl groups of the polyvinyl acetal resin in the first layer islower than a content ratio of hydroxyl groups of the polyvinyl acetalresin in the second layer.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, the glasstransition temperature of the first layer is lower than a glasstransition temperature of the second layer.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, an absolute valueof a difference between the glass transition temperature of the firstlayer and the glass transition temperature of the second layer is 30° C.or higher.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, the interlayer filmfurther includes a third layer containing a polyvinyl acetal resin and aplasticizer, in which the third layer is disposed on a second surfaceside of the first layer that is opposite to the first surface.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, each of the firstlayer, the second layer, and the third layer contains a plasticizer.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, provided that athickness of the interlayer film for laminated glass is T, a thicknessof the first layer is 0.4 T or less.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, when laminatedglass is obtained by interposing the interlayer film for laminated glassbetween two sheets of green glass having a thickness of 2 mm based onJIS R3208, a visible light transmittance of the obtained laminated glassis 70% or greater.

In a certain aspect of the interlayer film for laminated glass accordingto one or more embodiments of the present invention, the interlayer filmfor laminated glass is used with a first glass plate with a thickness ofequal to or less than 1 mm and arranged between the first glass plateand a second glass plate to be used for obtaining laminated glass.

According to one or more embodiments of the present invention, there isprovided laminated glass including a first lamination glass member, asecond lamination glass member, and the aforementioned interlayer filmfor laminated glass, in which the interlayer film for laminated glass isdisposed between the first lamination glass member and the secondlamination glass member.

In a certain aspect of the laminated glass according to one or moreembodiments of the present invention, the first lamination glass memberis a first glass plate, and a thickness of the first glass plate is 1 mmor less.

An interlayer film for laminated glass according to one or moreembodiments of the present invention includes a first layer containing athermoplastic resin, in which a glass transition temperature of thefirst layer is 10° C. or lower, and an equivalent stiffness of theinterlayer film at 25° C. is 2.4 MPa or greater. Therefore, bendingrigidity of laminated glass including the interlayer film can beimproved, and sound insulating properties of the interlayer film can beimproved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view schematically showing an interlayer film forlaminated glass according to one or more embodiments of the presentinvention.

FIG. 2 is a sectional view schematically showing an interlayer film forlaminated glass according to one or more embodiments of the presentinvention.

FIG. 3 is a sectional view schematically showing an example of laminatedglass including the interlayer film for laminated glass shown in FIG. 1.

FIG. 4 is a sectional view schematically showing an example of laminatedglass including the interlayer film for laminated glass shown in FIG. 2.

FIG. 5 is a schematic view for illustrating a method for measuringbending rigidity.

DESCRIPTION OF EMBODIMENTS

Hereinafter, one or more embodiments of the present invention will bespecifically described.

An interlayer film for laminated glass (in the present specification,simply described as an “interlayer film” in some cases) according to oneor more embodiments of the present invention has a single-layerstructure or two or more-layer structure. The interlayer film accordingto one or more embodiments of the present invention may have asingle-layer structure or two or more-layer structure. Furthermore, theinterlayer film according to one or more embodiments of the presentinvention may have a structure consisting of two layers or three or morelayers. The interlayer film according to one or more embodiments of thepresent invention has a first layer containing a thermoplastic resin.The interlayer film according to one or more embodiments of the presentinvention may be a single-layered interlayer film including only thefirst layer or a multilayered interlayer film including the first layerand other layers.

In the interlayer film according to one or more embodiments of thepresent invention, a glass transition temperature of the first layer is10° C. or lower.

An equivalent stiffness of the interlayer film according to one or moreembodiments of the present invention at 25° C. is 2.4 MPa or greater.

Because of being constituted as above, the interlayer film according toone or more embodiments of the present invention can improve bendingrigidity of laminated glass including the interlayer film. In order toobtain laminated glass, the interlayer film is disposed between a firstglass plate and a second glass plate in many cases. Even though thefirst glass plate has a small thickness, in a case where the interlayerfilm according to one or more embodiments of the present invention isused, bending rigidity of the laminated glass can be sufficientlyimproved. Furthermore, even though both of the first and second glassplates have a small thickness, in a case where the interlayer filmaccording to one or more embodiments of the present invention is used,bending rigidity of the laminated glass can be sufficiently improved.Herein, in a case where both of the first and second glass plates have agreat thickness, bending rigidity of the laminated glass is furtherimproved.

Furthermore, because of being constituted as above, the interlayer filmaccording to one or more embodiments of the present invention canimprove sound insulating properties of laminated glass including theinterlayer film.

The aforementioned interlayer film may have a structure consisting oftwo or more layers, and may include a second layer in addition to thefirst layer. The interlayer film may further include the second layercontaining a thermoplastic resin. In a case where the interlayer filmincludes the second layer, the second layer is disposed on a firstsurface side of the first layer.

The aforementioned interlayer film may have a structure consisting ofthree or more layers, and may include a third layer in addition to thefirst and second layers. The interlayer film may further include thethird layer containing a thermoplastic resin. In a case where theinterlayer film includes the second and third layers, the third layer isdisposed on a second surface side of the first layer that is opposite tothe first surface described above.

A surface of the aforementioned second layer that is opposite to theaforementioned first layer side may be a surface on which a laminationglass member or a glass plate is laminated. A thickness of the glassplate laminated on the second layer may be 1 mm or less. The secondsurface of the first layer that is opposite to the first surface(surface on the second layer side) may be a surface on which alamination glass member or a glass plate is laminated. A thickness ofthe glass plate laminated on the first layer may be 1 mm or less. Asurface of the third layer that is opposite to the first layer side maybe a surface on which a lamination glass member or a glass plate islaminated. A thickness of the glass plate laminated on the third layermay be 1 mm or less.

Due to the interlayer film, bending rigidity can be sufficientlyimproved. Therefore, the interlayer film is suitably used for obtaininglaminated glass by using a first glass plate having a thickness of 1 mmor less and disposing the interlayer film between the first glass plateand a second glass plate. Furthermore, due to the interlayer film,bending rigidity can be sufficiently improved. Accordingly, theinterlayer film is more suitably used for obtaining laminated glass byusing the first glass plate having a thickness of 1 mm or less and asecond glass plate having a thickness of 1 mm or less and disposing theinterlayer film between the first glass plate and the second glassplate.

Hereinafter, one or more embodiments of the present invention will bedescribed with reference to drawings.

FIG. 1 is a sectional view schematically showing an interlayer film forlaminated glass according to one or more embodiments of the presentinvention.

An interlayer film 11 shown in FIG. 1 is a multilayered interlayer filmhaving a structure consisting of two or more layers. The interlayer film11 is used for obtaining laminated glass. The interlayer film 11 is aninterlayer film for laminated glass. The interlayer film 11 includes afirst layer 1, a second layer 2, and a third layer 3. On a first surface1 a of the first layer 1, the second layer 2 is disposed and laminated.On a second surface 1 b of the first layer 1 that is opposite to thefirst surface 1 a, the third layer 3 is disposed and laminated. Thefirst layer 1 is an intermediate layer. Each of the second layer 2 andthe third layer 3 is a protective layer, and in examples of the presentembodiment, each of the second layer 2 and the third layer 3 is asurface layer. The first layer 1 is disposed and interposed between thesecond layer 2 and the third layer 3. Accordingly, the interlayer film11 has multilayer structure (second layer 2/first layer 1/third layer 3)in which the second layer 2, the first layer 1, and the third layer 3are laminated in this order.

Between the second layer 2 and the first layer 1 and between the firstlayer 1 and the third layer 3, other layers may be disposed. The secondlayer 2 and the first layer 1 may be directly laminated on each other,and the first layer 1 and the third layer 3 may be directly laminated oneach other. Examples of other layers include a layer containingpolyethylene terephthalate and the like.

The first layer 1 contains a thermoplastic resin. The second layer 2 maycontain a thermoplastic resin. The third layer 3 may contain athermoplastic resin.

FIG. 2 is a sectional view schematically showing an interlayer film forlaminated glass according to one or more embodiments of the presentinvention.

An interlayer film 11A shown in FIG. 2 is a single-layered interlayerfilm having a structure consisting of a single layer. The interlayerfilm 11A is a first layer. The interlayer film 11A is used for obtaininglaminated glass. The interlayer film 11A is an interlayer film forlaminated glass. The interlayer film 11A (first layer) contains athermoplastic resin.

The interlayer film may include a first layer as a layer which is anintermediate layer in the interlayer film or a layer which is not asurface layer in the interlayer film. The interlayer film may include asecond layer as a surface layer in the interlayer film. The interlayerfilm may include a third layer as a surface layer in the interlayerfilm.

Hereinafter, the first layer, the second layer, and the third layerconstituting the interlayer film according to one or more embodiments ofthe present invention and each of the components contained in the firstlayer, the second layer, and the third layer will be specificallydescribed.

(Thermoplastic Resin)

The aforementioned first layer contains a thermoplastic resin(hereinafter, described as a thermoplastic resin (1) in some cases). Theaforementioned first layer may contain, as the thermoplastic resin (1),a polyvinyl acetal resin (hereinafter, described as a polyvinyl acetalresin (1) in some cases). The aforementioned second layer may contain athermoplastic resin (hereinafter, described as a thermoplastic resin (2)in some cases) and may contain, as the thermoplastic resin (2), apolyvinyl acetal resin (hereinafter, described as a polyvinyl acetalresin (2) in some cases). The aforementioned third layer may contain athermoplastic resin (hereinafter, described as a thermoplastic resin (3)in some cases) and may contain, as the thermoplastic resin (3), apolyvinyl acetal resin (hereinafter, described as a polyvinyl acetalresin (3) in some cases). The thermoplastic resin (1), the thermoplasticresin (2), and the thermoplastic resin (3) may be the same as ordifferent from each other. Therefore, it is possible that thethermoplastic resin (1) is different from the thermoplastic resin (2)and the thermoplastic resin (3), because then sound insulatingproperties are further improved. The polyvinyl acetal resin (1), thepolyvinyl acetal resin (2), and the polyvinyl acetal resin (3) may bethe same as or different from each other. Therefore, it is possible thatthe polyvinyl acetal resin (1) is different from the polyvinyl acetalresin (2) and the polyvinyl acetal resin (3), because then soundinsulating properties are further improved. One kind of each of thethermoplastic resin (1), the thermoplastic resin (2), and thethermoplastic resin (3) may be used singly, or two or more kinds thereofmay be used in combination. One kind of each of the polyvinyl acetalresin (1), the polyvinyl acetal resin (2), and the polyvinyl acetalresin (3) may be used singly, or two or more kinds thereof may be usedin combination.

Examples of the thermoplastic resin include a polyvinyl acetal resin, anethylene-vinyl acetate copolymer resin, an ethylene-acrylic acidcopolymer resin, a polyurethane resin, a polyvinyl alcohol resin, andthe like. Thermoplastic resins other than these may also be used.

The aforementioned polyvinyl acetal resin can be manufactured by, forexample, acetalizing polyvinyl alcohol by using aldehyde. The polyvinylacetal resin may be an acetalization product of polyvinyl alcohol. Thepolyvinyl alcohol is obtained by, for example, saponifying polyvinylacetate. A degree of saponification of the polyvinyl alcohol isgenerally 70 to 99.9 mol %.

An average degree of polymerization of the aforementioned polyvinylalcohol (PVA) may be 200 or greater, 500 or greater, 1,500 or greater,1,600 or greater, 2,600 or greater, or 2,700 or greater. The averagedegree of polymerization of the polyvinyl alcohol may be 5,000 or less,4,000 or less, or 3,500 or less. In a case where the average degree ofpolymerization is equal to or greater than the aforementioned lowerlimit, penetration resistance of laminated glass is further improved. Ina case where the average degree of polymerization is equal to or lessthan the aforementioned upper limit, an interlayer film is easilyformed.

The average degree of polymerization of the polyvinyl alcohol isdetermined by a method based on JIS K6726 “Testing methods for polyvinylalcohol”.

The number of carbon atoms of an acetal group in the aforementionedpolyvinyl acetal resin may be 3 to 5, for example 4 or 5.

As the aforementioned aldehyde, generally, aldehyde having 1 to 10carbon atoms is suitably used. Examples of the aldehyde having 1 to 10carbon atoms include formaldehyde, acetaldehyde, propionaldehyde,n-butyraldehyde, isobutyraldehyde, n-valeraldehyde,2-ethylbutyraldehyde, n-hexylaldehyde, n-octylaldehyde, n-nonylaldehyde,n-decylaldehyde, benzaldehyde, and the like. Among these, acetaldehyde,propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-hexylaldehyde, orn-valeraldehyde may be used, acetaldehyde, propionaldehyde,n-butyraldehyde, isobutyraldehyde, or n-valeraldehyde may be used, andn-butyraldehyde or n-valeraldehyde may be used. One kind of the aldehydemay be used singly, or two or more kinds thereof may be used incombination.

A content ratio of hydroxyl groups (amount of hydroxyl groups) of thepolyvinyl acetal resin (1) may be 17 mol % or greater, 20 mol % orgreater, or 22 mol % or greater. The content ratio of hydroxyl groupsmay be 28 mol % or less, 27 mol % or less, 25 mol % or less, or 24 mol %or less. In a case where the content ratio of hydroxyl groups is equalto or greater than the aforementioned lower limit, mechanical strengthof the interlayer film is further improved. Particularly, in a casewhere the content ratio of hydroxyl groups of the polyvinyl acetal resin(1) is 20 mol % or greater, reaction efficiency becomes high, andproductivity becomes excellent. In a case where the content ratio ofhydroxyl groups is 28 mol % or less, sound insulating properties of thelaminated glass are further improved. In a case where the content ratioof hydroxyl groups is equal to or less than the aforementioned upperlimit, flexibility of the interlayer film is improved, and handling ofthe interlayer film becomes easy. Particularly, although laminated glassincluding the interlayer film, in which the content ratio of hydroxylgroups of the polyvinyl acetal resin (1) is 28 mol % or less, tends tohave low bending rigidity, in a case where the aforementioned firstlayer contains silica particles, bending rigidity can be markedlyimproved.

A content ratio of hydroxyl groups of each of the polyvinyl acetal resin(2) and the polyvinyl acetal resin (3) may be 25 mol % or greater, 28mol % or greater, 30 mol % or greater, 31.5 mol % or greater, 32 mol %or greater, or 33 mol % or greater. The content ratio of hydroxyl groupsmay be 38 mol % or less, 37 mol % or less, 36.5 mol % or less, or 36 mol% or less. In a case where the content ratio of hydroxyl groups is equalto or greater than the aforementioned lower limit, bending rigidity isfurther improved, and adhesion of the interlayer film is furtherimproved. In a case where the content ratio of hydroxyl groups is equalto or less than the aforementioned upper limit, flexibility of theinterlayer film is improved, and handling of the interlayer film becomeseasy.

From the viewpoint of further improving sound insulating properties, thecontent ratio of hydroxyl groups of the polyvinyl acetal resin (1) maybe lower than the content ratio of hydroxyl groups of the polyvinylacetal resin (2). In addition, from the viewpoint of further improvingsound insulating properties, the content ratio of hydroxyl groups of thepolyvinyl acetal resin (1) may be lower than the content ratio ofhydroxyl groups of the polyvinyl acetal resin (3). Moreover, from theviewpoint of further improving sound insulating properties, each of anabsolute value of a difference between the content ratio of hydroxylgroups of the polyvinyl acetal resin (1) and the content ratio ofhydroxyl groups of the polyvinyl acetal resin (2) and an absolute valueof a difference between the content ratio of hydroxyl groups of thepolyvinyl acetal resin (1) and the content ratio of hydroxyl groups ofthe polyvinyl acetal resin (3) may be 1 mol % or greater, 5 mol % orgreater, 9 mol % or greater, 10 mol % or greater, or 12 mol % orgreater. Each of the absolute value of the difference between thecontent ratio of hydroxyl groups of the polyvinyl acetal resin (1) andthe content ratio of hydroxyl groups of the polyvinyl acetal resin (2)and the absolute value of the difference between the content ratio ofhydroxyl groups of the polyvinyl acetal resin (1) and the content ratioof hydroxyl groups of the polyvinyl acetal resin (3) may be 20 mol % orless. In a case where silica particles are used, sound insulatingproperties tend to be further reduced due to the influence of silicaparticles, than in a case where silica particles are not used. However,in a case where the relationship of the content ratio of hydroxyl groupsdescribed above is satisfied, sound insulating properties can beeffectively improved.

The content ratio of hydroxyl groups of the polyvinyl acetal resin is avalue obtained by expressing a molar fraction, which is determined bydividing an amount of ethylene groups to which hydroxyl groups arebonded by a total amount of ethylene groups on a main chain, as apercentage. The amount of ethylene groups to which hydroxyl groups arebonded can be measured based on, for example, JIS K6728 “Testing methodsfor polyvinyl butyral”.

A degree of acetylation (amount of acetyl groups) of the polyvinylacetal resin (1) may be 0.01 mol % or greater, 0.1 mol % or greater, 7mol % or greater, or 9 mol % or greater. The degree of acetylation ofthe polyvinyl acetal resin (1) may be 30 mol % or less, 25 mol % orless, 24 mol % or less, or 20 mol % or less. In a case where the degreeof acetylation is equal to or greater than the aforementioned lowerlimit, compatibility between the polyvinyl acetal resin and aplasticizer is improved. In a case where the degree of acetylation isequal to or less than the aforementioned upper limit, moistureresistance of the interlayer film and the laminated glass is improved.Particularly, in a case where the degree of acetylation of the polyvinylacetal resin (1) is 0.1 to 25 mol %, penetration resistance becomesexcellent.

A degree of acetylation of each of the polyvinyl acetal resin (2) andthe polyvinyl acetal resin (3) may be 0.01 mol % or greater, for example0.5 mol % or greater. The degree of acetylation may be 10 mol % or less,for example 2 mol % or less. In a case where the degree of acetylationis equal to or greater than the aforementioned lower limit,compatibility between the polyvinyl acetal resin and a plasticizer isimproved. In a case where the degree of acetylation is equal to or lessthan the aforementioned upper limit, moisture resistance of theinterlayer film and the laminated glass is improved.

The degree of acetylation is a value obtained by expressing a molarfraction, which is determined by dividing an amount of ethylene groupsto which acetyl groups are bonded by a total amount of ethylene groupson a main chain, as a percentage. The amount of ethylene groups to whichacetyl groups are bonded can be measured based on, for example, JISK6728 “Testing methods for polyvinyl butyral”.

A degree of acetalization (in a case of polyvinyl butyral resin, adegree of butyralization) of the polyvinyl acetal resin (1) may be 47mol % or greater, for example 60 mol % or greater. The degree ofacetalization may be 85 mol % or less, 80 mol % or less, or 75 mol % orless. In a case where the degree of acetalization is equal to or greaterthan the aforementioned lower limit, compatibility between the polyvinylacetal resin and a plasticizer is improved. In a case where the degreeof acetalization is equal to or less than the aforementioned upperlimit, a reaction time necessary for manufacturing the polyvinyl acetalresin is shortened.

A degree of acetalization (in a case of polyvinyl butyral resin, adegree of butyralization) of each of the polyvinyl acetal resin (2) andthe polyvinyl acetal resin (3) may be 55 mol % or greater, for example60 mol % or greater. The degree of acetalization may be 75 mol % orless, for example 71 mol % or less. In a case where the degree ofacetalization is equal to or greater than the aforementioned lowerlimit, compatibility between the polyvinyl acetal resin and aplasticizer is improved. In a case where the degree of acetalization isequal to or less than the aforementioned upper limit, a reaction timenecessary for manufacturing the polyvinyl acetal resin is shortened.

The degree of acetalization is a value obtained by subtracting an amountof ethylene groups, to which hydroxyl groups are bonded, and an amountof ethylene groups, to which acetyl groups are bonded, from a totalamount of ethylene groups on a main chain, dividing a value obtained asabove by the total amount of ethylene groups on a main chain, andexpressing a molar fraction obtained as above as a percentage.

The content ratio of hydroxyl groups (amount of hydroxyl groups), thedegree of acetalization (degree of butyralization), and the degree ofacetylation described above may be calculated from results measured bymethods based on JIS K6728 “Testing methods for polyvinyl butyral”.Here, the measurement based on ASTM D1396-92 may be used. In a casewhere the polyvinyl acetal resin is a polyvinyl butyral resin, thecontent ratio of hydroxyl groups (amount of hydroxyl groups), the degreeof acetalization (degree of butyralization), and the degree ofacetylation can be calculated from results measured by methods based onJIS K6728 “Testing methods for polyvinyl butyral”.

From the viewpoint of further improving penetration resistance of thelaminated glass, the polyvinyl acetal resin (1) may be a polyvinylacetal resin (A) having a degree of acetylation (a) of less than 8 mol %and a degree of acetalization (a) of 65 mol % or greater or a polyvinylacetal resin (B) having a degree of acetylation (b) of 8 mol % orgreater. The polyvinyl acetal resin (2) and the polyvinyl acetal resin(3) may be the polyvinyl acetal resin (A) or the polyvinyl acetal resin(B).

The degree of acetylation (a) of the polyvinyl acetal resin (A) may beless than 8 mol %, 7.9 mol % or less, 7.8 mol % or less, 6.5 mol % orless, or 6 mol % or less. The degree of acetylation (a) may be 0.1 mol %or greater, 0.5 mol % or greater, 2 mol % or greater, 5 mol % orgreater, or 5.5 mol % or greater. In a case where the degree ofacetylation (a) is 0.1 mol % or greater and less than 8 mol %, migrationof a plasticizer can be easily controlled, and sound insulatingproperties of the laminated glass are further improved.

The degree of acetalization (a) of the polyvinyl acetal resin (A) may be65 mol % or greater, 66 mol % or greater, 67 mol % or greater, 67.5 mol% or greater, or 75 mol % or greater. The degree of acetalization (a)may be 85 mol % or less, 84 mol % or less, 83 mol % or less, or 82 mol %or less. In a case where the degree of acetalization (a) is equal to orgreater than the aforementioned lower limit, sound insulating propertiesof the laminated glass are further improved. In a case where the degreeof acetalization (a) is equal to or less than the aforementioned upperlimit, a reaction time necessary for manufacturing the polyvinyl acetalresin (A) can be shortened.

A content ratio (a) of a hydroxyl group of the polyvinyl acetal resin(A) may be 18 mol % or greater, 19 mol % or greater, 20 mol % orgreater, 21 mol % or greater, or 23 mol % or greater. The content ratio(a) of the hydroxyl group may be 31 mol % or less, 30 mol % or less, 29mol % or less, or 28 mol % or less. In a case where the content ratio(a) of the hydroxyl group is equal to or greater than the aforementionedlower limit, adhesion of the aforementioned second layer is furtherimproved. In a case where the content ratio (a) of the hydroxyl group isequal to or less than the aforementioned upper limit, sound insulatingproperties of the laminated glass are further improved.

A degree of acetylation (b) of the polyvinyl acetal resin (B) may be 8mol % or greater, 9 mol % or greater, 9.5 mol % or greater, 10 mol % orgreater, or 10.5 mol % or greater. The degree of acetylation (b) may be30 mol % or less, 28 mol % or less, 26 mol % or less, or 24 mol % orless. In a case where the degree of acetylation (b) is equal to orgreater than the aforementioned lower limit, sound insulating propertiesof the laminated glass are further improved. In a case where the degreeof acetylation (b) is equal to or less than the aforementioned upperlimit, a reaction time necessary for manufacturing the polyvinyl acetalresin (B) can be shortened.

A degree of acetalization (b) of the polyvinyl acetal resin (B) may be50 mol % or greater, 53 mol % or greater, 55 mol % or greater, or 60 mol% or greater. The degree of acetalization (b) may be 78 mol % or less,75 mol % or less, 72 mol % or less, or 70 mol % or less. In a case wherethe degree of acetalization (b) is equal to or greater than theaforementioned lower limit, sound insulating properties of the laminatedglass are further improved. In a case where the degree of acetalization(b) is equal to or less than the aforementioned upper limit, a reactiontime necessary or manufacturing the polyvinyl acetal resin (B) can beshortened.

A content ratio (b) of a hydroxyl group of the polyvinyl acetal resin(B) may be 18 mol % or greater, 19 mol % or greater, 20 mol % orgreater, 21 mol % or greater, or 23 mol % or greater. The content ratio(b) of the hydroxyl group may be 31 mol % or less, 30 mol % or less, 29mol % or less, or 28 mol % or less. In a case where the content ratio(b) of the hydroxyl group is equal to or greater than the aforementionedlower limit, adhesion of the aforementioned second layer is furtherimproved. In a case where the content ratio (b) of the hydroxyl group isequal to or less than the aforementioned upper limit, sound insulatingproperties of the laminated glass are further improved.

Each of the polyvinyl acetal resin (A) and the polyvinyl acetal resin(B) may be a polyvinyl butyral resin.

(Plasticizer)

The aforementioned first layer (including a single-layered interlayerfilm) may contain a plasticizer (hereinafter, described as a plasticizer(1) in some cases). The aforementioned second layer may contain aplasticizer (hereinafter, described as a plasticizer (2) in some cases).Furthermore, the aforementioned third layer may contain a plasticizer(hereinafter, described as a plasticizer (3) in some cases). Thecombination use of the plasticizer or the use of the polyvinyl acetalresin and the plasticizer appropriately improves the adhesion of thelayer including the polyvinyl acetal resin and the plasticizer to alamination glass member or other layers. The plasticizer is notparticularly limited. The plasticizers (1), (2), and (3) may be the sameas or different from each other. One kind of each of the plasticizers(1), (2), and (3) may be used singly, or two or more kinds thereof maybe used in combination.

Examples of the aforementioned plasticizer include organic esterplasticizers such as a monobasic organic acid ester and a polybasicorganic acid ester, organic phosphoric acid plasticizers such as anorganic phosphoric acid plasticizer and an organic phosphorous acidplasticizer, and the like. Among these, organic ester plasticizers maybe used. The aforementioned plasticizer may be a liquid plasticizer.

Examples of the aforementioned monobasic organic acid ester include aglycol ester obtained by reacting glycol with a monobasic organic acid,and the like. Examples of the glycol include triethylene glycol,tetraethylene glycol, tripropylene glycol, and the like. Examples of themonobasic organic acid include butyric acid, isobutyric acid, caproicacid, 2-ethyl butyrate, heptanoic acid, n-octylic acid, 2-ethylhexanoicacid, n-nonylic acid, decylic acid, and the like.

Examples of the aforementioned polybasic organic acid ester include anester compound of a polybasic organic acid and an alcohol having alinear or branched structure containing 4 to 8 carbon atoms, and thelike. Examples of the polybasic organic acid include adipic acid,sebacic acid, azelaic acid, and the like.

Examples of the aforementioned organic ester plasticizers includetriethylene glycol-di-2-ethyl propanoate, triethylene glycol-di-2-ethylbutyrate, triethylene glycol-di-2-ethyl hexanoate, triethylene glycoldicaprylate, triethylene glycol di-n-octanoate, triethylene glycoldi-n-heptanoate, tetraethylene glycol di-n-heptanoate, dibutyl sebacate,dioctyl azelate, dibutyl carbitol adipate, ethylene glycol di-2-ethylbutyrate, 1,3-propylene glycol di-2-ethyl butyrate, 1,4-butylene glycoldi-2-ethyl butyrate, diethylene glycol di-2-ethyl butyrate, diethyleneglycol di-2-ethyl hexanoate, dipropylene glycol di-2-ethyl butyrate,triethylene glycol di-2-ethyl pentanoate, tetraethylene glycoldi-2-ethyl butyrate, diethylene glycol dicaprylate, dihexyl adipate,dioctyl adipate, cyclohexyl hexyl adipate, a mixture of heptyl adipateand nonyl adipate, diisononyl adipate, diisodecyl adipate, heptyl nonyladipate, dibutyl sebacate, oil-modified alkyd sebacate, a mixture of aphosphoric acid ester and an adipic acid ester, and the like. Organicester plasticizers other than these may also be used, and an adipic acidester other than the aforementioned adipic acid ester may also be used.

Examples of the aforementioned organic phosphoric acid plasticizersinclude tributoxyethyl phosphate, isodecylphenyl phosphate, triisopropylphosphate, and the like.

The aforementioned plasticizer may be a diester plasticizer representedby the following Formula (1).

In Formula (1), each of R1 and R2 represents an organic group having 2to 10 carbon atoms, R3 represents an ethylene group, an isopropylenegroup, or a n-propylene group, and p represents an integer of 3 to 10.Each of R1 and R2 in Formula (1) may be an organic group having 5 to 10carbon atoms or an organic group having 6 to 10 carbon atoms.

The aforementioned plasticizer may include di-(2-butoxyethyl)-adipate(DBEA), triethylene glycol di-2-ethylhexanoate (3GO), triethylene glycoldi-2-ethylbutyrate (3GH), or triethylene glycol di-2-ethylpropanoate. Itmay include triethylene glycol di-2-ethylhexanoate (3GO), triethyleneglycol di-2-ethylbutyrate (3GH), or triethylene glycoldi-2-ethylpropanoate. It may include triethylene glycoldi-2-ethylhexanoate or triethylene glycol di-2-ethylbutyrate. It mayinclude triethylene glycol di-2-ethylhexanoate.

Each of a content of the plasticizer (2) (hereinafter, described as acontent (2) in some cases) with respect to 100 parts by weight of thethermoplastic resin (2) and a content of the plasticizer (3)(hereinafter, described as a content (3) in some cases) with respect to100 parts by weight of the thermoplastic resin (3) may be 10 parts byweight or greater, 15 parts by weight or greater, 20 parts by weight orgreater, or 24 parts by weight or greater. Each of the content (2) andthe content (3) may be 40 parts by weight or less, 35 parts by weight orless, 32 parts by weight or less, or 30 parts by weight or less. In acase where each of the content (2) and the content (3) is equal to orgreater than the aforementioned lower limit, flexibility of theinterlayer film is improved, and handling of the interlayer film becomeseasy. In a case where each of the content (2) and the content (3) isequal to or less than the aforementioned upper limit, bending rigidityis further improved.

A content of the plasticizer (1) (hereinafter, described as a content(1) in some cases) with respect to 100 parts by weight of thethermoplastic resin (1) may be 50 parts by weight or greater, 55 partsby weight or greater, or 60 parts by weight or greater. The content (1)may be 100 parts by weight or less, 90 parts by weight or less, 85 partsby weight or less, or 80 parts by weight or less. In a case where thecontent (1) is equal to or greater than the aforementioned lower limit,flexibility of the interlayer film is improved, and handing of theinterlayer film becomes easy. In a case where the content (1) is equalto or less than the aforementioned upper limit, penetration resistanceof the laminated glass is further improved.

In order to improve sound insulating properties of the laminated glass,the content (1) may be greater than the content (2) and the content (3).Particularly, although laminated glass including an interlayer film inwhich the content (1) is 55 parts by weight or greater tends to have lowbending rigidity, in a case where the aforementioned first layercontains silica particles, bending rigidity can be markedly improved.

From the viewpoint of further improving sound insulating properties ofthe laminated glass, each of an absolute value of a difference betweenthe content (2) and the content (1) and an absolute value of adifference between the content (3) and the content (1) may be 10 partsby weight or greater, 15 parts by weight or greater, or 20 parts byweight or greater. Each of the absolute value of the difference betweenthe content (2) and the content (1) and the absolute value of thedifference between the content (3) and the content (1) may be 80 partsby weight or less, 75 parts by weight or less, or 70 parts by weight orless.

(Silica Particles)

The aforementioned first layer may contain silica particles. The use ofsilica particles further improves bending rigidity without deterioratingsound insulating properties, and improves the adhesion betweenrespective layers. One kind of the silica particles may be used singly,or two or more kinds thereof may be used in combination.

A specific surface area of the silica particles determined by a BETmethod may be 50 m²/g or greater, 100 m²/g or greater, 200 m²/g orgreater, 250 m²/g or greater, or 300 m²/g or greater. The specificsurface area of the silica particles may be 500 m²/g or less. Thespecific surface area can be measured by a gas adsorption method byusing a specific surface area/pore size distribution analyzer. Examplesof the analyzer include “ASAP 2420” manufactured by ShimadzuCorporation, and the like.

A content of the silica particles with respect to 100 parts by weight ofthe thermoplastic resin (1) may be 1 part by weight or greater, 5 partsby weight or greater, 10 parts by weight or greater, or 15 parts byweight or greater. The content of the silica particles may be 70 partsby weight or less, 64 parts by weight or less, 60 parts by weight orless, 55 parts by weight or less, 45 parts by weight or less, or 35parts by weight or less. In a case where the content of the silicaparticles is equal to or greater than the aforementioned lower limit,the adhesion between respective layers is further improved, and bendingrigidity is further improved. In a case where the content of the silicaparticles is equal to or less than the aforementioned upper limit, soundinsulating properties are further improved.

(Heat Shielding Compound)

The aforementioned interlayer film may contain a heat shieldingcompound. Furthermore, each of the aforementioned first layer, secondlayer, and third layer may contain a heat shielding compound. One kindof the heat shielding compound may be used singly, or two or more kindsthereof may be used in combination.

Component X:

The aforementioned interlayer film may contain, as a component X, atleast one kind of compound among a phthalocyanine compound, anaphthalocyanine compound, and an anthracyanine compound. Each of theaforementioned first layer, second layer, and third layer may containthe component X. The component X is a heat shielding compound. One kindof the component X may be used singly, or two or more kinds thereof maybe used in combination.

The component X is not particularly limited. As the component X, it ispossible to use a phthalocyanine compound, a naphthalocyanine compound,and an anthracyanine compound known in the related art.

From the viewpoint of further improving heat shielding properties of theinterlayer film and the laminated glass, the component X may be at leastone kind of compound selected from the group consisting ofphthalocyanine, a phthalocyanine derivative, naphthalocyanine, and anaphthalocyanine derivative. It may be at least one kind of compoundbetween phthalocyanine and a phthalocyanine derivative.

From the viewpoint of effectively improving heat shielding propertiesand maintaining a visible light transmittance at a much higher levelover a long period of time, the component X may contain a vanadium atomor a copper atom. The component X may contain either a vanadium atom ora copper atom. The component X may be at least one kind of compoundbetween phthalocyanine containing a vanadium atom or a copper atom and aphthalocyanine derivative containing a vanadium atom or a copper atom.From the viewpoint of further improving heat shielding properties of theinterlayer film and the laminated glass, the component X may have astructural unit in which an oxygen atom is bonded to a vanadium atom.

A content of the component X in 100% by weight of the layer (the firstlayer, the second layer, or the third layer) containing the component Xmay be 0.001% by weight or greater, 0.005% by weight or greater, 0.01%by weight or greater, or 0.02% by weight or greater. The content of thecomponent X may be 0.2% by weight or less, 0.1% by weight or less, 0.05%by weight or less, or 0.04% by weight or less. In a case where thecontent of the component X is equal to or greater than theaforementioned lower limit and equal to or less than the aforementionedupper limit, heat shielding properties are sufficiently improved, and avisible light transmittance is sufficiently improved. For example, thevisible light transmittance can become 70% or greater.

Heat Shielding Particles:

The aforementioned interlayer film may contain heat shielding particles.Each of the aforementioned first layer, second layer, and third layermay contain the heat shielding particles. The heat shielding particlesare a heat shielding compound. The use of the heat shielding particlesmakes it possible to effectively block infrared rays (heat rays). Onekind of the heat shielding particles may be used singly, or two or morekinds thereof may be used in combination.

From the viewpoint of further improving heat shielding properties of thelaminated glass, the heat shielding particles may be metal oxideparticles. The heat shielding particles may be particles formed of ametal oxide (metal oxide particles).

Infrared rays having a wavelength of 780 nm or greater that is longerthan a wavelength of visible light have a small energy amount comparedto ultraviolet rays. However, infrared rays exert a strong thermaleffect and are released as heat when being absorbed into a substance.Therefore, infrared rays are generally called heat rays. The use of theheat shielding particles makes it possible to effectively block infraredrays (heat rays). The heat shielding particles refer to particles thatcan absorb infrared rays.

Specific examples of the heat shielding particles include metal oxideparticles such as aluminum-doped tin oxide particles, indium-doped tinoxide particles, antimony-doped tin oxide particles (ATO particles),gallium-doped zinc oxide particles (GZO particles), indium-doped zincoxide particles (IZO particles), aluminum-doped zinc oxide particles(AZO particles), niobium-doped titanium oxide particles, sodium-dopedtungsten oxide particles, cesium-doped tungsten oxide particles,thallium-doped tungsten oxide particles, rubidium-doped tungsten oxideparticles, tin-doped indium oxide particles (ITO particles), tin-dopedzinc oxide particles, and silicon-doped zinc oxide particles, lanthanumhexaboride (LaB₆) particles, and the like. Heat shielding particlesother than these may also be used. Among these, metal oxide particlesmay be used because these particles have a high function of blockingheat rays. The metal oxide particles may be ATO particles, GZOparticles, IZO particles, ITO particles, or tungsten oxide particles.They may be ITO particles or tungsten oxide particles. Especially,tin-doped indium oxide particles (ITO particles) may be used becausethese particles have a high function of blocking heat rays and areeasily obtained, and tungsten oxide particles may also be used.

From the viewpoint of further improving heat shielding properties of theinterlayer film and the laminated glass, the tungsten oxide particlesmay be metal-doped tungsten oxide particles. The “tungsten oxideparticles” include metal-doped tungsten oxide particles. Specificexamples of the metal-doped tungsten oxide particles includesodium-doped tungsten oxide particles, cesium-doped tungsten oxideparticles, thallium-doped tungsten oxide particles, rubidium-dopedtungsten oxide particles, and the like.

From the viewpoint of further improving heat shielding properties of theinterlayer film and the laminated glass, cesium-doped tungsten oxideparticles may be used. From the viewpoint of further improving heatshielding properties of the interlayer film and the laminated glass, thecesium-doped tungsten oxide particles may be tungsten oxide particlesrepresented by Formula: Cs_(0.33)WO₃.

An average particle size of the heat shielding particles may be 0.01 μmor greater, for example 0.02 μm or greater. The average particle sizemay be 0.1 μm or less, for example 0.05 μm or less. In a case where theaverage particle size is equal to or greater than the aforementionedlower limit, shielding properties for heat rays are sufficientlyimproved. In a case where the average particle size is equal to or lessthan the aforementioned upper limit, dispersibility of the heatshielding particles is improved.

The aforementioned “average particle size” means a volume averageparticle size. The volume average particle size can be measured using aparticle size distribution analyzer (“UPA-EX150” manufactured by NIKKISOCO., LTD.) or the like.

A content of the heat shielding particles in 100% by weight of the layer(the first layer, the second layer, or the third layer) containing theheat shielding particles may be 0.01% by weight or greater, 0.1% byweight or greater, 1% by weight or greater, or 1.5% by weight orgreater. The content of the heat shielding particles may be 6% by weightor less, 5.5% by weight or less, 4% by weight or less, 3.5% by weight orless, or 3% by weight or less. In a case where the content of the heatshielding particles is equal to or greater than the aforementioned lowerlimit and equal to or less than the aforementioned upper limit, heatshielding properties are sufficiently improved, and a visible lighttransmittance is sufficiently improved.

(Metal Salt)

The aforementioned interlayer film may contain at least one kind ofmetal salt (hereinafter, described as a metal salt M in some cases)among alkali metal salts and alkaline earth metal salts. Each of theaforementioned first layer, second layer, and third layer may containthe metal salt M. The use of the metal salt M makes it easy to controladhesiveness between the interlayer film and the lamination glass memberor the adhesiveness between the respective layers in the interlayerfilm. One kind of the metal salt M may be used singly, or two or morekinds thereof may be used in combination.

The metal salt M may contain at least one kind of metal selected fromthe group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr, and Ba. The metalsalt contained in the interlayer film may contain at least one kind ofmetal between K and Mg.

The metal salt M may be an alkali metal salt of an organic acid having 2to 16 carbon atoms or an alkaline earth metal salt of an organic acidhaving 2 to 16 carbon atoms, for example a magnesium carboxylic acidsalt having 2 to 16 carbon atoms or a potassium carboxylic acid salthaving 2 to 16 carbon atoms.

The magnesium carboxylic acid salt having 2 to 16 carbon atoms and thepotassium carboxylic acid salt having 2 to 16 carbon atoms are notparticularly limited, and examples thereof include magnesium acetate,potassium acetate, magnesium propionate, potassium propionate, magnesium2-ethylbutyrate, potassium 2-ethylbutanoate, magnesium 2-ethylhexanoate,potassium 2-ethylhexanoate, and the like.

A total content of Mg and K in the layer (the first layer, the secondlayer, or the third layer) containing the metal salt M may be 5 ppm orgreater, 10 ppm or greater, or 20 ppm or greater. The total content ofMg and K may be 300 ppm or less, 250 ppm or less, or 200 ppm or less. Ina case where the total content of Mg and K is equal to or greater thanthe aforementioned lower limit and equal to or less than theaforementioned upper limit, adhesiveness between the interlayer film andthe lamination glass member or adhesiveness between the respectivelayers in the interlayer film can be controlled much better.

(UV Shielding Agent)

The aforementioned interlayer film may contain a UV shielding agent.Each of the aforementioned first layer, second layer, and third layermay contain a UV shielding agent. The use of the UV shielding agent morereliably prevents a visible light transmittance from decreasing even ifthe interlayer film and the laminated glass are used for a long periodof time. One kind of the UV shielding agent may be used singly, or twoor more kinds thereof may be used in combination.

The UV shielding agent includes a UV absorber. The UV shielding agentmay be a UV absorber.

Examples of the UV shielding agent include a UV shielding agentcontaining a metal atom, a UV shielding agent containing a metal oxide,a UV shielding agent having a benzotriazole structure, a UV shieldingagent having a benzophenone structure, a UV shielding agent having atriazine structure, a UV shielding agent having a malonic acid esterstructure, a UV shielding agent having an oxalic acid anilide structure,a UV shielding agent having a benzoate structure, and the like.

Examples of the aforementioned UV absorber containing a metal atominclude platinum particles, platinum particles whose surfaces are coatedwith silica, palladium particles, palladium particles whose surfaces arecoated with silica, and the like. It is possible that the UV shieldingagent is not heat shielding particles.

The aforementioned UV shielding agent may be a UV shielding agent havinga benzotriazole structure, a UV shielding agent having a benzophenonestructure, a UV shielding agent having a triazine structure, or a UVshielding agent having a benzoate structure. It may be a UV shieldingagent having a benzotriazole structure or a UV shielding agent having abenzophenone structure. It may be a UV absorber having a benzotriazolestructure.

Examples of the aforementioned UV absorber containing a metal oxideinclude zinc oxide, titanium oxide, cerium oxide, and the like. Thesurface of the UV absorber containing a metal oxide may be coated.Examples of materials, with which the surface of the UV absorbercontaining a metal oxide is coated, include an insulative metal oxide, ahydrolysable organic silicon compound, a silicone compound, and thelike.

Examples of the aforementioned UV absorber having a benzotriazolestructure include UV absorbers having a benzotriazole structure, such as2-(2′-hydroxy-5′-methylphenyl)benzotriazole (“Tinuvin P” manufactured byBASF SE), 2-(2′-hydroxy-3′,5′-di-t-butylphenyl)benzotriazole (“Tinuvin320” manufactured by BASF SE),2-(2′-hydroxy-3′-t-butyl-5-methylphenyl)-5-chlorobenzotriazole (“Tinuvin326” manufactured by BASF SE), and2-(2′-hydroxy-3′,5′-di-amylphenyl)benzotriazole (“Tinuvin 328”manufactured by BASF SE). The above UV shielding agent may be a UVabsorber having a benzotriazole structure containing a halogen atom, forexample a UV absorber having a benzotriazole structure containing achlorine atom, because these have excellent UV absorbing performance.

Examples of the aforementioned UV absorber having a benzophenonestructure include octabenzone (“Chimassorb 81” manufactured by BASF SE)and the like.

Examples of the aforementioned UV absorber having a triazine structureinclude “LA-F70” manufactured by ADEKA Corporation,2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol (“Tinuvin1577FF” manufactured by BASF SE), and the like.

Examples of the UV shielding agent having a malonic acid ester structureinclude dimethyl 2-(p-methoxybenzylidene)malonate,tetraethyl-2,2-(1,4-phenylenedimethylidene)bismalonate,2-(p-methoxybenzylidene)-bis(1,2,2,6,6-pentamethyl4-piperidinyl)malonate, and the like.

Examples of commercially available products of the UV shielding agenthaving a malonic acid ester structure include Hostavin B-CAP, HostavinPR-25, and Hostavin PR-31 (all manufactured by Clariant InternationalLtd.).

Examples of the aforementioned UV shielding agent having an oxalic acidanilide structure include oxalic acid diamides having a substituted arylgroup on a nitrogen atom, such asN-(2-ethylphenyl)-N′-(2-ethoxy-5-t-butylphenyl)oxalic acid diamide,N-(2-ethylphenyl)-N′-(2-ethoxy-phenyl)oxalic acid diamide, and2-ethyl-2′-ethoxy-oxyanilide (“Sanduvor VSU” manufactured by ClariantInternational Ltd.).

Examples of the aforementioned UV absorber having a benzoate structureinclude 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate(“Tinuvin 120” manufactured by BASF SE) and the like.

From the viewpoint of further inhibiting a decrease in a visible lighttransmittance after a passage of time, a content of the UV shieldingagent in 100% by weight of the layer (the first layer, the second layer,or the third layer) containing the UV shielding agent may be 0.1% byweight or greater, 0.2% by weight or greater, 0.3% by weight or greater,or 0.5% by weight or greater. The content of the UV shielding agent maybe 2.5% by weight or less, 2% by weight or less, 1% by weight or less,or 0.8% by weight or less. Particularly, in a case where the content ofthe UV shielding agent in 100% by weight of the layer containing the UVshielding agent is 0.2% by weight or greater, a decrease in a visiblelight transmittance of the interlayer film and the laminated glass thatoccurs after a passage of time can be markedly inhibited.

(Antioxidant)

The aforementioned interlayer film may contain an antioxidant. Each ofthe aforementioned first layer, second layer, and third layer maycontain an antioxidant. One kind of the antioxidant may be used singly,or two or more kinds thereof may be used in combination.

Examples of the antioxidant include a phenol-based antioxidant, asulfur-based antioxidant, a phosphorus-based antioxidant, and the like.The phenol-based antioxidant is an antioxidant having a phenol skeleton.The sulfur-based antioxidant is an antioxidant containing a sulfur atom.The phosphorus-based antioxidant is an antioxidant containing aphosphorus atom.

The antioxidant may be a phenol-based antioxidant or a phosphorus-basedantioxidant.

Examples of the aforementioned phenol-based antioxidant include2,6-di-t-butyl-p-cresol (BHT), butylated hydroxyanisole (BHA),2,6-di-t-butyl-4-ethylphenol,stearyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate,2,2′-methylenebis-(4-methyl-6-butylphenol),2,2′-methylenebis-(4-ethyl-6-t-butylphenol),4,4′-butylidene-bis-(3-methyl-6-t-butylphenol),1,1,3-tris-(2-methyl-hydroxy-5-t-butylphenyl)butane, tetrakis[methylene-3-(3′,5′-butyl-4-hydroxyphenyl)propionate]methane,1,3,3-tris-(2-methyl-4-hydroxy-5-t-butylphenol)butane,1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene,bis(3,3′-t-butylphenol)butyric acid glycol ester,bis(3-t-butyl-4-hydroxy-5-methylbenzenepropanoate)ethylenebis(oxyethylene), and the like. One kind or two ormore kinds among these antioxidants are suitably used.

Examples of the aforementioned phosphorus-based antioxidant includetridecyl phosphite, tris(tridecyl) phosphite, triphenyl phosphite,trinonylphenyl phosphite, bis(tridecyl)pentaerythritol diphosphite,bis(decyl)pentaerythritol diphosphite,tris(2,4-di-t-butylphenyl)phosphite,bis(2,4-di-t-butyl-6-methylphenyl)ethyl ester phosphorous acid,tris(2,4-di-t-butylphenyl)phosphite,2,2′-methylenebis(4,6-di-t-butyl-1-phenyloxy)(2-ethylhexyloxy)phosphorus, and the like. One kind or two or more kindsamong these antioxidants are suitably used.

Examples of commercially available products of the above antioxidantsinclude “IRGANOX 245” manufactured by BASF SE, “IRGAFOS 168”manufactured by BASF SE, “IRGAFOS 38” manufactured by BASF SE,“SUMILIZER BHT” manufactured by Sumitomo Chemical Industry CompanyLimited, “IRGANOX 1010” manufactured by BASF SE, and the like.

In order to maintain a high visible light transmittance of theinterlayer film and the laminated glass for a long period of time, acontent of the aforementioned antioxidant in 100% by weight of theinterlayer film or in 100% by weight of the layer (the first layer, thesecond layer, or the third layer) containing the antioxidant may be 0.1%by weight or greater. Furthermore, because the effects obtained by theaddition of the antioxidant are saturated, the content of theantioxidant in 100% by weight of the interlayer film or in 100% byweight of the layer containing the antioxidant may be 2% by weight orless.

(Other Components)

If necessary, each of the aforementioned first layer, second layer, andthird layer may contain additives such as a coupling agent containingsilicon, aluminum, or titanium, a dispersant, a surfactant, a flameretardant, an antistatic agent, a pigment, a dye, an adhesion adjuster,a moisture proof agent, a fluorescent whitening agent, and an infraredabsorber. One kind of these additives may be used singly, or two or morekinds thereof may be used in combination.

(Other Details of Interlayer Film for Laminated Glass)

From the viewpoint of improving bending rigidity of the laminated glass,an equivalent stiffness of the interlayer film at 25° C. is 2.4 MPa orgreater. From the viewpoint of further improving bending rigidity of thelaminated glass, the equivalent stiffness of the interlayer film at 25°C. may be 3 MPa or greater, 4 MPa or greater, 5 MPa or greater, or 9 MPaor greater. The equivalent stiffness of the interlayer film at 25° C.may be 30 MPa or less, for example 20 MPa or less.

In order to improve equivalent stiffness, the first layer may containsilica particles. Furthermore, in order to improve equivalent stiffness,a degree of cross-linking of the thermoplastic resin in the first layermay be appropriately increased. Moreover, in order to improve equivalentstiffness, the thickness of each layer may be appropriately selected.

From the viewpoint of further improving sound insulating properties ofthe laminated glass, the glass transition temperature of the first layermay be 15° C. or lower, 10° C. or lower, 5° C. or lower, or 0° C. orlower. The glass transition temperature of the first layer may be −20°C. or higher.

From the viewpoint of further improving bending rigidity of thelaminated glass, the glass transition temperature of the first layer maybe lower than a glass transition temperature of the second and thirdlayers. In a case where the first layer having a glass transitiontemperature lower than that of the second and third layers containssilica particles, and the interlayer film includes the second and thirdlayers having a glass transition temperature higher than that of thefirst layer, bending rigidity of the laminated glass is markedlyimproved. From the viewpoint of further improving bending rigidity ofthe laminated glass, an absolute value of a difference between the glasstransition temperature of the first layer and the glass transitiontemperature of the second and third layers may be 10° C. or higher, 20°C. or higher, 30° C. or higher, or 35° C. or higher. The absolute valueof the difference between the glass transition temperature of the firstlayer and the glass transition temperature of the second and thirdlayers may be 70° C. or lower.

The glass transition temperature can be measured by, for example, amethod in which immediately after the obtained interlayer film is storedfor 12 hours in an environment with a room temperature that equals 23±2°C. and a humidity that equals 25±5%, viscoelasticity thereof is measuredusing a viscoelasticity analyzer “DVA-200” manufactured by IT KeisokuSeigyo Co., Ltd. The glass transition temperature may be measured underthe conditions in which the interlayer film is cut in 8 mm (length)×5 mm(width) and heated in a shear mode up to 100° C. from −30° C. at a rateof temperature increase of 5° C./min, a frequency of 1 Hz, and a strainof 0.08%.

From the viewpoint of improving bending rigidity of the laminated glass,a Young's modulus of the first layer at 25° C. may be 0.4 MPa orgreater, 0.5 MPa or greater, 0.6 MPa or greater, or 0.8 MPa or greater.The Young's modulus may be 6 MPa or less, 5 MPa or less, 4 MPa or less,or 2.5 MPa or less.

From the viewpoint of improving bending rigidity of the laminated glass,a Young's modulus of each of the second and third layers at 25° C. maybe 3 MPa or greater, 10 MPa or greater, 25 MPa or greater, or 100 MPa orgreater. The Young's modulus may be 700 MPa or less, more preferably 500MPa or less, for example 400 MPa or less.

In order to adjust the Young's modulus within an appropriate range, thefirst layer may contain silica particles. Furthermore, in order toadjust the Young's modulus within an appropriate range, a degree ofcross-linking of the thermoplastic resin in the first layer may beappropriately increased.

A thickness of the aforementioned interlayer film is not particularlylimited. From the viewpoint of practically and from the viewpoint ofsufficiently improving penetration resistance and bending rigidity ofthe laminated glass, the thickness of the interlayer film may be 0.1 mmor greater, for example 0.25 mm or greater. The thickness of theinterlayer film may be 3 mm or less, 2 mm or less, or 1.5 mm or less. Ina case where the thickness of the interlayer film is equal to or greaterthan the aforementioned lower limit, penetration resistance and bendingrigidity of the laminated glass are improved. In a case where thethickness of the interlayer film is equal to or less than theaforementioned upper limit, transparency of the interlayer film isfurther improved.

The thickness of the interlayer film is denoted by T. A thickness of theaforementioned first layer may be 0.0625 T or greater, for example 0.1 Tor greater. The thickness of the first layer may be 0.4 T or less, 0.375T or less, 0.25 T or less, or 0.15 T or less. In a case where thethickness of the first layer is 0.4 T or less, bending rigidity isfurther improved.

A thickness of each of the aforementioned second and third layers may be0.3 T or greater, 0.3125 T or greater, or 0.375 T or greater. Thethickness of each of the second and third layers may be 0.9375 T orless, for example 0.9 T or less. The thickness of each of the second andthird layers may be 0.468751 or less or 0.451 or less. In a case wherethe thickness of each of the second and third layers is equal to orgreater than the aforementioned lower limit and equal to or less thanthe aforementioned upper limit, rigidity and sound insulating propertiesof the laminated glass are further improved.

A total thickness of the aforementioned second and third layers may be0.625 T or greater, 0.75 T or greater, or 0.85 T or greater. The totalthickness of the second and third layers may be 0.9375 T or less, forexample 0.9 T or less. In a case where the total thickness of the secondand third layers is equal to or greater than the aforementioned lowerlimit and equal to or less than the aforementioned upper limit, rigidityand sound insulating properties of the laminated glass are furtherimproved.

A method for manufacturing the interlayer film according to one or moreembodiments of the present invention is not particularly limited. In acase where a single-layered interlayer film is manufactured, examples ofthe method for manufacturing the interlayer film according to one ormore embodiments of the present invention include a method of extrudinga resin composition by using an extruder. In a case where a multilayeredinterlayer film is manufactured, examples of the method formanufacturing the interlayer film according to one or more embodimentsof the present invention include a method of forming each layer by usingeach resin composition for forming each layer and then, for example,laminating the obtained each layer, a method of laminating each layer byco-extruding each resin composition for forming each layer by using anextruder, and the like. A manufacturing method using extrusion moldingmay be used because this method is suitable for continuous production.

The aforementioned second and third layers may contain the samepolyvinyl acetal resin, and may contain the same polyvinyl acetal resinand the same plasticizer, because then manufacturing efficiency of theinterlayer film becomes excellent. For the same reason, the second andthird layers may be formed of the same resin composition.

According to one or more embodiments of the present invention, theaforementioned interlayer film has shapes of recesses and protrusions onat least one of the both surfaces thereof, and may have shapes ofrecesses and protrusions on both surfaces thereof. A method for formingthe shapes of recesses and protrusions is not particularly limited, andexamples thereof include a lip embossing method, an embossing rollmethod, a calendar roll method, a profile extrusion method, and thelike. Among these, an embossing roll method may be used because thismethod makes it possible to form a large number of shapes of recessesand protrusions that are quantitatively constant recess and protrusionpatterns.

(Laminated Glass)

FIG. 3 is a sectional view schematically showing an example of laminatedglass including the interlayer film for laminated glass shown in FIG. 1.

Laminated glass 31 shown in FIG. 3 includes a first lamination glassmember 21, a second lamination glass member 22, and the interlayer film11. The interlayer film 11 is disposed and interposed between the firstlamination glass member 21 and the second lamination glass member 22.

The first lamination glass member 21 is laminated on a first surface 11a of the interlayer film 11. The second lamination glass member 22 islaminated on a second surface 11 b of the interlayer film 11 that isopposite to the first surface 11 a. The first lamination glass member 21is laminated on a surface 2 a of the second layer 2 that faces outside.The second lamination glass member 22 is laminated on a surface 3 a ofthe third layer 3 that faces outside.

FIG. 4 is a sectional view schematically showing an example of laminatedglass including the interlayer film for laminated glass shown in FIG. 2.

Laminated glass 31A shown in FIG. 4 has the first lamination glassmember 21, the second lamination glass member 22, and the interlayerfilm 11A. The interlayer film 11A is disposed and interposed between thefirst lamination glass member 21 and the second lamination glass member22.

The first lamination glass member 21 is laminated on a first surface 11a of the interlayer film 11A. The second lamination glass member 22 islaminated on a second surface 11 b of the interlayer film 11A that isopposite to the first surface 11 a.

As described above, the laminated glass according to one or moreembodiments of the present invention includes the first lamination glassmember, the second lamination glass member, and the interlayer film, andthe interlayer film is the interlayer film for laminated glass accordingto one or more embodiments of the present invention. In the laminatedglass according to one or more embodiments of the present invention, theinterlayer film is disposed between the first lamination glass memberand the second lamination glass member.

Examples of the aforementioned lamination glass members include a glassplate, a polyethylene terephthalate (PET) film, and the like. Thelaminated glass includes not only laminated glass in which an interlayerfilm is interposed between two sheets of glass plates but also laminatedglass in which an interlayer film is interposed between a glass plateand a PET film or the like. The laminated glass is a laminate includinga glass plate, and at least one sheet of glass plate may be used in thelaminated glass.

Examples of the glass plate include inorganic glass and organic glass.Examples of the inorganic glass include float plate glass, heatray-absorbing plate glass, heat ray-reflecting plate glass, polishedplate glass, figured glass, wired plate glass, and the like. The organicglass is synthetic resin glass as a substitute for inorganic glass.Examples of the organic glass include a polycarbonate plate, apoly(meth)acrylic resin plate, and the like. Examples of thepoly(meth)acrylic resin plate include a polymethyl (meth)acrylate plateand the like.

A thickness of the aforementioned lamination glass member may be 1 mm orgreater. The thickness of the lamination glass member may be 5 mm orless, for example 3 mm or less. In a case where the lamination glassmember is a glass plate, a thickness of the glass plate may be 0.5 mm orgreater, for example 0.7 mm or greater. The thickness of the glass platemay be 5 mm or less, for example 3 mm or less. In a case where thelamination glass member is a PET film, a thickness of the PET film maybe 0.03 mm to 0.5 mm.

The use of the interlayer film according to one or more embodiments ofthe present invention makes it possible to maintain bending rigidity ofthe laminated glass at a high level even if the laminated glass has asmall thickness. From the viewpoint of lightening the laminated glass,reducing an environmental load by reducing the amount of materials ofthe laminated glass, or reducing an environmental load by improving fuelefficiency of an automobile by means of lightening the laminated glass,the thickness of the aforementioned glass plate may be 2 mm or less, 1.8mm or less, 1.5 mm or less, 1 mm or less, 0.8 mm or less, or 0.7 mm orless.

A method for manufacturing the laminated glass is not particularlylimited. For example, the interlayer film is interposed between theaforementioned first and second lamination glass members and aspiratedunder reduced pressure by being passed through pressing rolls or putinto a rubber bag such that air remaining between the first laminationglass member, the second lamination glass member, and the interlayerfilm is removed. Then, the first and second lamination glass members andthe interlayer film are preliminarily bonded to each other at atemperature of about 70° C. to 110° C., thereby obtaining a laminate.Next, the laminate is put into an autoclave or pressed, andpressure-bonded at a temperature of about 120° C. to 150° C. under apressure of 1 to 1.5 MPa. The laminated glass can be obtained in thisway. At the time of manufacturing the laminated glass as above, thefirst layer, the second layer, and the third layer may be laminated.

The interlayer film and the laminated glass described above can be usedin automobiles, railroad cars, airplanes, ships, buildings, and thelike. Furthermore, the interlayer film and the laminated glass can alsobe used for other purposes. The interlayer film and the laminated glassmay be an interlayer film and laminated glass for cars or buildings.They may be an interlayer film and laminated glass for cars. Theinterlayer film and the laminated glass can be used in front glass, sideglass, rear glass, and roof glass of automobiles, and the like. Theinterlayer film and the laminated glass are suitably used inautomobiles. The interlayer film is used for obtaining laminated glassfor automobiles.

From the viewpoint of obtaining laminated glass having much bettertransparency, the aforementioned visible light transmittance of thelaminated glass may be 65% or greater, for example 70% or greater. Thevisible light transmittance of the laminated glass can be measured basedon JIS R3211 (1998). The visible light transmittance of the laminatedglass, which is obtained by interposing the interlayer film forlaminated glass according to one or more embodiments of the presentinvention between two sheets of green glass (heat ray-absorbing plateglass) having a thickness of 2 mm based on JIS R3208, may be 70% orgreater. The visible light transmittance may be 75% or greater.

Hereinafter, one or more embodiments of the present invention will bemore specifically described based on examples, but the present inventionis not limited to the examples.

The following materials were prepared.

(Polyvinyl Acetal Resin)

Polyvinyl acetal resins shown in the following Tables 1 to 4 wereappropriately used. For acetalization of all of the polyvinyl acetalresins used, n-butyraldehyde having 4 carbon atoms was used.

For the polyvinyl acetal resins, a degree of acetalization (degree ofbutyralization), a degree of acetylation, and a content ratio ofhydroxyl groups were measured by the methods based on JIS K6728 “Testingmethods for polyvinyl butyral”. Herein, in a case where the degree ofacetalization, the degree of acetylation, and the content ratio ofhydroxyl groups were measured according to ASTM D1396-92, the sameresults were obtained as in a case where the methods based on JIS K6728“Testing methods for polyvinyl butyral” were used.

(Plasticizer)

Triethylene glycol di-2-ethylhexanoate (3GO)

Di-(2-butoxyethyl)-adipate (DBEA)

(Silica Particles)

Silica particles (a) (“AEROSIL 380” manufactured by NIPPON AEROSIL CO.,LTD., specific surface area determined by a BET method: 380±30 m²/g)

Silica particles (b) (“BZ-400” manufactured by Tosoh Silica Corporation,specific surface area determined by a BET method: 450 m²/g)

Silica particles (c) (“AZ-204” manufactured by Tosoh Silica Corporation,specific surface area determined by a BET method: 300 m²/g)

Silica particles (d) (“AZ-201” manufactured by Tosoh Silica Corporation,specific surface area determined by a BET method: 300 m²/g)

(UV Shielding Agent)

Tinuvin 326(2-(2′-hydroxy-3′-t-butyl-5-methylphenyl)-5-chlorobenzotriazole,“Tinuvin 326” manufactured by BASF SE)

(Antioxidant)

BHT (2,6-di-t-butyl-p-cresol)

Example 1

Preparation of Composition for Forming First Layer:

100 parts by weight of a polyvinyl acetal resin of a kind shown in thefollowing Table 1, 60 parts by weight of the plasticizer (3GO), 20 partsby weight of the silica particles (a), 0.2 parts by weight of the UVshielding agent (Tinuvin 326), and 0.2 parts by weight of theantioxidant (BHT) were mixed together, thereby obtaining a compositionfor forming a first layer.

Preparation of Composition for Forming Second Layer and Third Layer:

100 parts by weight of a polyvinyl acetal resin of a kind shown in thefollowing Table 1, 24 parts by weight of the plasticizer (3GO), 0.2parts by weight of the UV shielding agent (Tinuvin 326), and 0.2 partsby weight of the antioxidant (BHT) were mixed together, therebyobtaining a composition for forming a second layer and a third layer.

Preparation of Interlayer Film:

The composition for forming the first layer and the composition orforming the second and third layers were co-extruded using aco-extruder, thereby preparing an interlayer film (thickness: 780 μm)having a laminated structure consisting of the second layer (thickness:340 μm)/the first layer (thickness: 100 μm)/the third layer (thickness:340 μm).

Preparation of Laminated Glass A (for Measuring Bending Rigidity):

Two glass plates (clear float glass, 25 cm (length)×10 cm (width)×2.5 mm(thickness)) that were washed and dried were prepared. The interlayerfilm obtained as above was interposed between the two glass plates,thereby obtaining a laminate. The obtained laminate was put into arubber bag and deaerated for 20 minutes at a degree of vacuum of 2,660Pa (20 torr). Then, the laminate was held in an autoclave in thedeaerated state for 30 minutes at 90° C., and in this state, thelaminate was pressed in a vacuum. The laminate preliminarilypressure-bonded in this way was pressure-bonded in the autoclave for 20minutes under the conditions of a temperature of 135° C. and a pressureof 1.2 MPa (12 kg/cm²), thereby obtaining laminated glass A.

Preparation of Laminated Glass B (for Measuring Bending Rigidity):

One glass plate (clear float glass, 25 cm (length)×10 cm (width)×2.5 mm(thickness)) that was washed and dried was prepared. Furthermore, oneglass plate (Gorilla glass 2, 25 cm (length)×10 cm (width)×0.7 mm(thickness)) that was washed and dried was prepared. Laminated glass Bwas obtained in the same manner as used for obtaining the laminatedglass A, except that the aforementioned two glass plates were used.

Preparation of Laminated Glass C (for Measuring Bending Rigidity):

Two glass plates (Gorilla glass 2, 25 cm (length)×10 cm (width)×0.7 mm(thickness)) that were washed and dried were prepared. Laminated glass Cwas obtained in the same manner as used for obtaining the laminatedglass A, except that the aforementioned two glass plates were used.

Preparation of Laminated Glass F (for Measuring Bending Rigidity):

One glass plate (clear float glass, 25 cm (length)×10 cm (width)×1.8 mm(thickness)) that was washed and dried was prepared. Furthermore, oneglass plate (clear float glass, 25 cm (length)×10 cm (width)×1.0 mm(thickness)) that was washed and dried was prepared. Laminated glass Fwas obtained in the same manner as used for obtaining the laminatedglass A, except that the aforementioned two glass plates were used.

Preparation of Laminated Glass D (for Measuring Sound InsulatingProperties):

The obtained interlayer film was cut in a size of 30 cm (length)×2.5 cm(width). Then, the interlayer film was interposed between two sheets ofgreen glass (30 cm (length)×2.5 cm (width)×2 mm (thickness)) based onJIS R3208, thereby obtaining a laminate. The laminate was put into arubber bag, deaerated for 20 minutes at a degree of vacuum of 2.6 kPa.Then, the laminate was moved to an oven in the deaerated state, held for30 minutes at 90° C., and pressed in a vacuum such that the laminate waspreliminarily pressure-bonded. In an autoclave, the preliminarilypressure-bonded laminate was pressure-bonded for 20 minutes under theconditions of a temperature of 135° C. and a pressure of 1.2 MPa,thereby obtaining laminated glass D.

Preparation of Laminated Glass E (for Measuring Visible LightTransmittance):

The obtained interlayer film was cut in a size of 5 cm (length)×5 cm(width). Then, two sheets of green glass (5 cm (length)×5 cm (width)×2mm (thickness)) based on JIS R3208 were prepared. The obtainedinterlayer film was interposed between the two sheets of green glass,the resultant was held in a vacuum laminator for 30 minutes at 90° C.,and pressed in a vacuum, thereby obtaining a laminate. In the laminate,the portion of the interlayer film sticking out of the glass plate wascut off, thereby obtaining laminated glass E.

Examples 2 to 38 and Comparative Examples 1 to 3

An interlayer film and laminated glass were obtained in the same manneras in Example 1, except that the type and the formulation amount of thepolyvinyl acetal resin, the plasticizer, and the silica particles usedin the composition for forming the first layer and the composition forforming the second and third layers were set as shown in the followingTables 1 to 4, and a thickness of each of the first layer, the secondlayer, and the third layer was set as shown in the following Tables 1 to4. Furthermore, in Examples 2 to 38 and Comparative Examples 1 to 3, thesame type of UV shielding agent and antioxidant as in Example 1 wereformulated in the same formulation amount (0.2 parts by weight withrespect to 100 parts by weight of the polyvinyl acetal resin) as inExample 1.

(Evaluation)

(1) Glass Transition Temperature

The obtained interlayer film was stored for 12 hours in an environmentwith room temperature that equaled 23±2° C. and a humidity that equaled25±5%. Immediately after the storage, by using a viscoelasticityanalyzer “DVA-200” manufactured by IT Keisoku Seigyo Co., Ltd.,viscoelasticity of the interlayer film was measured. The sample was cutin a size of 8 mm (length)×5 mm (width), and the viscoelasticity thereofwas measured under the conditions in which the sample was heated in ashear mode up to 100° C. from −30° C. at a rate of temperature increaseof 5° C./min, a frequency of 1 Hz, and a strain of 0.08%. Among theobtained measurement results, a peak temperature of a loss tangent wastaken as a glass transition temperature Tg (° C.). Tg resulting from thefirst layer was lower than Tg resulting from the second and thirdlayers.

(2) Young's Modulus

The composition for forming a first layer was mixed and press-molded at150° C., thereby obtaining a molded material (first layer) having athickness of 800 μm. The obtained molded material was punched by SuperDumbbell Cutter: SDK-600 manufactured by DUMBBELL CO., LTD., therebyobtaining a test piece. The obtained test piece was stored for 12 hoursat a temperature of 23° C. and a humidity of 30% RH. Then, in athermostatic chamber with a temperature of 25° C., a tensile test wasperformed on the test piece at 200 mm/min by using Tensilon manufacturedby A&D Company, Limited. A slope of the obtained stress-strain curve inan infinitesimal strain region was calculated and adopted as a Young'smodulus. Herein, the test piece may be obtained in a manner in which thefirst layer, which is obtained by peeling off the second and thirdlayers from the interlayer film in an environment with a temperature of23° C., is press-molded at 150° C. (for 10 minutes at 150° C. in anon-pressurized state and for 10 minutes at 150° C. in a pressurizedstate) such that a thickness thereof becomes 800 μm, and then punched bySuper Dumbbell Cutter: SDK-600 manufactured by DUMBBELL CO., LTD.

Specifically, the composition for forming a first layer was mixed andpress-molded at 150° C., thereby obtaining a molded material (firstlayer) having a thickness of 800 μm. The obtained molded material waspunched by Super Dumbbell Cutter: SDK-600 manufactured by DUMBBELL CO.,LTD., thereby obtaining a test piece having a total length of 120 mm.The obtained test piece was stored for 12 hours at a temperature of 23°C. and a humidity of 30% RH. Within the test piece, marker lines(distance between marker lines: 40 mm) were drawn in positions 40 mmdistant from both ends of the test piece, and a thickness of the testpiece between the marker lines was measured. Thicknesses of the testpiece in the respective marker line portions and the thickness of thetest piece between the two marker lines were measured, and an average ofthe thicknesses was taken as a thickness between the marker lines. Thethickness was measured using “Digimatic Indicator” (ID-C112C)manufactured by Mitutoyo Corporation. Then, in a thermostatic chamberwith a temperature of 25° C., by using Tensilon “RTE-1210” manufacturedby A&D Company Limited, a tensile test was performed on the test pieceat 200 mm/min and a distance between clamping jaws of 7 cm. By thefollowing equation, a stress and a strain were calculated.Stress=load/initial sectional area between marker linesStrain=(increase of distance between clamping jaws/initial distancebetween marker lines)×100

A slope, at which a strain became 0% to 10%, of the obtainedstress-strain curve was taken as a Young's modulus.

(3) Bending Rigidity

The laminated glass A, the laminated glass B, the laminated glass C, andthe laminated glass F obtained as above were prepared. In the laminatedglass A, the laminated glass B, the laminated glass C, and the laminatedglass F, the following glass plates were used.

Laminated glass A: two glass plates (clear float glass, 25 cm(length)×10 cm (width)×2.5 mm (thickness))

Laminated glass B: one glass plate (clear float glass, 25 cm (length)×10cm (width)×2.5 mm (thickness)) and one glass plate (Gorilla glass 2, 25cm (length)×10 cm (width)×0.7 mm (thickness))

Laminated glass C: two glass plates (Gorilla glass 2, 25 cm (length)×10cm (width)×0.7 mm (thickness))

Laminated glass F: one glass plate (clear float glass, 25 cm (length)×10cm (width)×1.8 mm (thickness)) and one glass plate (clear float glass,25 cm (length)×10 cm (width)×1.0 mm (thickness))

By a testing method schematically illustrated in FIG. 5, bendingrigidity was evaluated. As a measurement device, a universal materialtesting machine 5966 manufactured by Instron Japan Company Ltd.including a static 3-point bending test jig 2810 was used. Under themeasurement conditions of a measurement temperature of 20±3° C., adistance D1 of 18 cm, and a distance D2 of 25 cm, the laminated glasswas distorted in an F direction at a displacement rate of 1 mm/min, astress at the time when a displacement of 1.5 mm was applied thereto wasmeasured, and bending rigidity was calculated.

(4) Sound Insulating Properties

The laminated glass D was vibrated by a vibration generator (“vibratorG21-005D” manufactured by Shinken Co., Ltd.) for a damping test, andvibration characteristics obtained from the laminated glass D wereamplified using a mechanical impedance analyzer (“XG-81” manufactured byRION Co., Ltd.), and a vibration spectrum thereof was analyzed using aFFT spectrum analyzer (“FFT analyzer HP3582A” manufactured by YokogawaHewlett-Packard, Ltd.).

From a ratio of a loss factor obtained as above to a resonant frequencyof the laminated glass, a graph showing a relationship between a soundfrequency (Hz) and an acoustic transmission loss (dB) at 20° C. wasplotted, and a minimum acoustic transmission loss (TL value) at around asound frequency of 2,000 Hz was determined. The greater the TL value,the better the sound insulating properties. The sound insulatingproperties were judged based on the following criteria.

[Criteria for Judging Sound Insulating Properties]

◯: A TL value was 35 dB or greater.

X: A TL value was less than 35 dB.

(5) Visible Light Transmittance (a Light, Y Value, Initial A-Y (380 to780 nm))

BY using a spectrophotometer (“U-4100” manufactured by HitachiHigh-Technologies Corporation.), a visible light transmittance of theobtained laminated glass E at a wavelength of 380 to 780 nm was measuredbased on JIS R3211 (1998). The visible light transmittance was judgedbased on the following criteria.

[Criteria for Judging Visible Light Transmittance]

◯: A visible light transmittance was 70% or greater.

X: A visible light transmittance was less than 70%.

(6) Equivalent Stiffness

The composition for forming the second and third layers was mixed andpress-molded at 150° C., thereby obtaining a molded material (firstlayer) having a thickness of 800 μm. The obtained molded material waspunched by Super Dumbbell Cutter: SDK-600 manufactured by DUMBBELL CO.,LTD., thereby obtaining a test piece. The obtained test piece was storedfor 12 hours at a temperature of 23° C. and a humidity of 30% RH. Then,in a thermostatic chamber with a temperature of 25° C., a tensile testwas performed on the test piece at 200 mm/min by using Tensilonmanufactured by A&D Company, Limited. A slope of the obtainedstress-strain curve in an infinitesimal strain region was calculated andadopted as a Young's modulus. Specifically, the young's modulus wasmeasured in the same manner as used for measuring the young's modulus ofthe first layer, except that a slope at which a strain became 0% to 3%was taken as a Young's modulus.

Herein, the test piece may be obtained in a manner in which the firstlayer, which was obtained by peeling off the second and third layersfrom the interlayer film in an environment with a temperature of 23° C.,was press-molded at 150° C. (for 10 minutes at 150° C. in anon-pressurized state and for 10 minutes at 150° C. in a pressurizedstate) such that a thickness thereof becomes 800 μm, and then punched bySuper Dumbbell Cutter: SDK-600 manufactured by DUMBBELL CO., LTD.

From the Young's modulus and thickness of each of the first, second, andthird layers, an equivalent stiffness E* of the interlayer film wascalculated by an equation (X). The thicknesses of the first, second, andthird layers were measured by observing sections of the first, second,and third layers by using an optical microscope.E*=(Σiai)/(Σiai/Σi)  Equation (X):

In Equation (X), Ei represents a Young's modulus of a film of an ithlayer, and ai represents a thickness of a film of an ith layer. Σi meansthat the values of i layers are summed up.

Details and results of the above tests are shown in the following Tables1 to 4. In the following Tables 1 to 4, formulated components other thanthe polyvinyl acetal resin, the plasticizer, and the silica particlesare not described.

TABLE 1 Comparative Comparative Comparative Example Example ExampleExample Example Example Example Example Example Example 1 2 3 4 5 1 2 36 7 Composition Thickness μm 100 100 100 100 100 100 100 100 60 60 offirst layer Poly vinyl Average degree of 1700 2500 1700 3000 1700 17002300 3000 1700 2500 acetal resin polymerization of PVA Content ratio ofhydroxyl Mol % 21.2 20.8 21.2 23.3 21.2 23.1 23.0 23.3 21.2 20.8 groupsDegree of acetylation Mol % 12.6 23.5 12.6 12.0 12.6 11.8 11.5 12.0 12.623.5 Degree of acetalization Mol % 66.2 55.7 66.2 64.7 66.2 65.1 65.564.7 66.2 55.7 Content Part by Weight 100 100 100 100 100 100 100 100100 100 Plasticizer Type 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO ContentPart by Weight 60 60 60 60 60 60 60 60 60 60 Silica particles Type a a aa b — — — a a Content Part by Weight 20 20 5 5 20 — — — 20 20 Glasstransition temperature ° C. −0.15 −1.57 0.25 2.11 −0.25 2.21 2.16 2.06−0.18 −1.52 Young's modulus MPa 1.25 1.29 0.65 0.65 1.12 0.45 0.44 0.471.23 1.25 Composition of Thickness of each layer μm 340 340 340 340 340340 340 340 360 360 second and third Poly vinyl Average degree of 17001700 1700 1700 1700 1700 1700 1700 1700 1700 layers acetal resinpolymerization of PVA Content ratio of hydroxyl Mol % 34.5 34.5 34.530.1 34.5 30.1 30.1 30.1 34.5 34.5 groups Degree of acetylation Mol %0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.0 0.8 Degree of acetalization Mol %64.7 64.7 64.7 69.1 64.7 69.1 69.1 69.1 65.5 64.7 Content Part by Weight100 100 100 100 100 100 100 100 100 100 Plasticizer Type 3GO 3GO 3GO 3GO3GO 3GO 3GO 3GO 3GO 3GO Content Part by Weight 24 24 24 38.5 24 38.538.5 38.5 24 24 Glass transition temperature ° C. 44.8 44.0 44.3 28.743.8 28.8 28.6 28.7 44.5 43.5 Young's modulus MPa 405.0 406.3 405.3 5.3405.0 5.2 5.1 5.3 410.0 402.1 Evaluation Bending Laminated glass A mm/N0.0034 0.0035 0.0045 0.0058 0.0043 0.0062 0.0061 0.0063 0.0033 0.0031rigidity Laminated glass B mm/N 0.0074 0.0073 0.0092 0.0109 0.00800.0113 0.0115 0.0111 0.0353 0.0064 Laminated glass C mm/N 0.0465 0.04580.0681 0.0895 0.0532 0.1065 0.1066 0.1060 0.0353 0.0352 Laminated glassF mm/N 0.0110 0.0109 0.0144 0.0179 0.0120 0.0206 0.0206 0.0205 0.00920.0091 Sound insulting properties: TL method ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Visiblelight transmittance ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Equivalent stiffness MPa 9.559.85 5.02 2.76 8.57 2.21 2.16 2.29 15.43 15.67

TABLE 2 Example Example Example Example Example Example Example ExampleExample Example 8 9 10 11 12 13 14 15 16 17 Composition Thickness μm 100100 100 100 100 100 100 100 100 100 of first layer Poly vinyl Averagedegree of 1700 1700 1700 1700 1700 1700 1700 1700 1700 2300 acetal resinpolymerization of PVA Content ratio of hydroxyl Mol % 23.1 23.1 23.123.1 21.2 23.1 23.1 23.1 21.1 20.8 groups Degree of acetylation Mol %12.5 12.5 12.5 12.5 12.6 12.5 12.5 12.5 1.6 1.6 Degree of acetalizationMol % 64.5 64.5 64.5 64.5 66.2 64.5 64.5 64.5 77.3 77.6 Content Part byWeight 100 100 100 100 100 100 100 100 100 100 Plasticizer Type 3GO 3GO3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO Content Part by Weight 60 60 60 60 60 6060 60 60 60 Silica particles Type c c c c c c c c c c Content Part byWeight 20 20 20 20 20 20 20 — 20 20 Glass transition temperature ° C.2.13 2.13 2.13 2.13 −0.12 2.13 2.13 2.13 3.87 3.74 Young's modulus MPa0.95 0.95 0.95 0.95 1.16 0.95 0.95 0.95 1.03 1.05 Composition ofThickness of each layer μm 340 340 340 340 340 340 340 340 340 340second and third Poly vinyl Average degree of 1700 1700 1700 1700 17001700 1700 1700 1700 1700 layers acetal resin polymerization of PVAContent ratio of hydroxyl Mol % 34.5 33.2 32.5 31.4 34.5 35.4 36.5 37.334.5 34.5 groups Degree of acetylation Mol % 0.8 0.8 0.8 0.8 0.8 0.8 0.80.8 0.8 0.8 Degree of acetalization Mol % 64.7 66 66.7 67.8 64.7 63.862.7 61.9 64.7 64.7 Content Part by Weight 100 100 100 100 100 100 100100 100 100 Plasticizer Type 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GOContent Part by Weight 32 34.1 35.3 37.3 28.6 30.2 28.3 26.8 31 31 Glasstransition temperature ° C. 37.3 34.4 32.8 30.3 39.8 39.3 41.8 43.6 39.940.3 Young's modulus MPa 54.9 28.4 19.9 11.4 96.4 86.6 151.4 227.1 99.3108.6 Evaluation Bending Laminated glass A mm/N 0.0044 0.0044 0.00450.0047 0.0038 0.0041 0.0041 0.0040 0.0040 0.0039 rigidity Laminatedglass B mm/N 0.0086 0.0085 0.0087 0.0091 0.0077 0.0081 0.0081 0.00800.0079 0.0079 Laminated glass C mm/N 0.0648 0.0613 0.0640 0.0702 0.05120.0570 0.0560 0.0556 0.0544 0.0537 Laminated glass F mm/N 0.0139 0.01350.0140 0.0150 0.0118 0.0128 0.0127 0.0126 0.0124 0.0123 Sound insultingproperties: TL method ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Visible light transmittance ○○ ○ ○ ○ ○ ○ ○ ○ ○ Equivalent stiffness MPa 6.63 6.04 5.59 4.71 8.36 6.907.11 7.21 7.50 7.68

TABLE 3 Example Example Example Example Example Example Example ExampleExample Example 18 19 20 21 22 23 24 25 26 27 Composition Thickness μm100 100 100 100 100 100 100 100 100 100 of first layer Polyvinyl Averagedegree of 1700 1700 1700 1700 1700 1700 1700 1700 1700 2300 acetal resinpolymerization of PVA Content ratio of hydroxyl Mol % 24.4 24.6 23.123.1 23.8 23.8 23.8 23.8 23.8 23.8 groups Degree of acetylation Mol %6.5 6.5 12.5 12.5 12.1 12.1 12.1 12.1 12.1 12.1 Degree of acetalizationMol % 69.1 68.9 64.5 64.5 64.1 64.1 64.1 64.1 64.1 64.1 Content Part byWeight 100 100 100 100 100 100 100 100 100 100 Plasticizer Type 3GO 3GO3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO Content Part by Weight 60 60 60 60 60 6060 60 60 60 Silica particles Type c c c c — — — — — — Content Part byWeight 20 20 20 20 — — — — — — Glass transition temperature ° C. 5.425.54 6.04 −5.32 2.21 2.21 2.21 2.21 2.21 2.21 Young's modulus MPa 1.151.07 1.59 0.63 0.51 0.51 0.51 0.51 0.51 0.51 Composition of Thickness ofeach layer μm 340 340 340 340 340 340 340 340 340 365 second and thirdPolyvinyl Average degree of 1700 1700 1700 1700 1700 1700 1700 1700 17001700 layers acetal resin polymerization of PVA Content ratio of hydroxylMol % 34.5 34.5 34.5 34.5 34.5 34.5 34.5 34.5 34.5 34.5 groups Degree ofacetylation Mol % 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Degree ofacetalization Mol % 64.7 64.7 64.7 64.7 64.7 64.7 64.7 64.7 64.7 64.7Content Part by Weight 100 100 100 100 100 100 100 100 100 100Plasticizer Type 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO Content Part byWeight 36 36 33 30 36 34 32 30 28 32 Glass transition temperature ° C.35.6 35.3 37.3 37.3 34.0 35.1 36.4 38.0 39.1 36.4 Young's modulus MPa37.3 35.2 54.9 54.9 26.0 33.4 44.6 64.1 82.1 44.6 Evaluation BendingLaminated glass A mm/N 0.0040 0.0041 0.0035 0.0048 0.0052 0.0052 0.00520.0051 0.0051 0.0041 rigidity Laminated glass B mm/N 0.0080 0.00810.0073 0.0092 0.0099 0.0099 0.0098 0.0097 0.0097 0.0082 Laminated glassC mm/N 0.0547 0.0569 0.0458 0.0731 0.0836 0.0824 0.0814 0.0805 0.08000.0585 Laminated glass F mm/N 0.0124 0.0128 0.0109 0.0152 0.0169 0.01670.0166 0.0164 0.0163 0.0129 Sound insulting properties: TL method ○ ○ ○○ ○ ○ ○ ○ ○ ○ Visible light transmittance ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Equivalentstiffness MPa 7.42 6.92 10.35 4.53 3.51 3.60 3.69 3.77 3.82 6.82

TABLE 4 Example Example Example Example Example Example Example ExampleExample Example Example 28 29 30 31 32 33 34 35 36 37 38 CompositionThickness μm 80 50 120 120 120 70 100 100 100 100 100 of first layerPolyvinyl Average degree of 1700 1700 1700 1700 1700 1700 1700 1700 17001700 1700 acetal resin polymerization of PVA Content ratio of hydroxylMol % 23.1 23.1 24.6 24.6 24.6 23.4 23.1 23.1 23.1 23.1 27.5 groupsDegree of acetylation Mol % 12.5 12.5 14.0 14.0 14.0 13.3 12.5 12.5 12.512.5 12.5 Degree of acetalization Mol % 64.5 64.5 61.4 61.4 61.4 63.364.5 64.5 64.5 64.5 60.0 Content Part by Weight 100 100 100 100 100 100100 100 100 100 100 Plasticizer Type 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO3GO DBEA Content Part by Weight 60 60 60 60 60 60 60 60 60 60 60 Silicaparticles Type c c d d d d c c c c c Content Part by Weight 20 20 20 2020 20 30 40 50 60 20 Glass transition temperature ° C. 2.13 2.13 3.423.42 3.42 2.03 2.36 2.58 2.75 2.77 0.34 Young's modulus MPa 0.95 0.951.11 1.11 1.11 1.03 1.27 1.58 1.88 2.18 0.92 Composition of Thickness ofeach layer μm 350 365 330 330 300 355 340 340 340 340 340 second andthird Polyvinyl Average degree of 1700 1700 1700 1700 1700 1700 17001700 1700 1700 1700 layers acetal resin polymerization of PVA Contentratio of hydroxyl Mol % 34.5 34.5 34.5 34.5 34.5 34.5 34.5 34.5 34.534.5 34.5 groups Degree of acetylation Mol % 0.8 0.8 0.8 0.8 0.8 0.8 0.80.8 0.8 0.8 0.8 Degree of acetalization Mol % 64.7 64.7 64.7 64.7 64.764.7 64.7 64.7 64.7 64.7 64.7 Content Part by Weight 100 100 100 100 100100 100 100 100 100 100 Plasticizer Type 3GO 3GO 3GO 3GO 3GO 3GO 3GO 3GO3GO 3GO DBEA Content Part by Weight 32 32 31 33 35 32 32 32 32 32 38.5Glass transition temperature ° C. 37.3 37.3 36.4 35.3 34.0 36.9 37.337.3 37.3 37.3 37.3 Young's modulus MPa 54.9 549 44.7 35.2 26.0 50.254.9 54.9 54.9 54.9 14.8 14.8Evaluation Bending Laminated glass A mm/N0.0042 0.0038 0.0039 0.0043 0.0044 0.0037 0.0035 0.0031 0.0027 0.00250.0046 rigidity Laminated glass B mm/N 0.0083 0.0076 0.0081 0.00840.0087 0.0075 0.0082 0.0076 0.0070 0.0063 0.0089 Laminated glass C mm/N0.0604 0.0511 0.0579 0.0617 0.0667 0.0486 0.0575 0.0508 0.0451 0.04510.0677 Laminated glass F mm/N 0.0132 0.0117 0.0128 0.0134 0.0142 0.01130.0128 0.0117 0.0108 0.0101 0.0146 Sound insulting properties: TL method○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Visible light transmittance ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○Equivalent stiffness MPa 8.04 11.83 6.35 6.15 5.85 9.50 8.57 10.29 11.9113.43 5.05

REFERENCE SIGNS LIST

-   -   1 . . . first layer    -   1 a . . . first surface    -   1 b . . . second surface    -   2 . . . second layer    -   2 a . . . surface facing outside    -   3 . . . third layer    -   3 a . . . surface facing outside    -   11 . . . interlayer film    -   11A . . . interlayer film (first layer)    -   11 a . . . first surface    -   11 b . . . second surface    -   21 . . . first lamination glass member    -   22 . . . second lamination glass member    -   31 . . . laminated glass    -   31A . . . laminated glass

Although the disclosure has been described with respect to only alimited number of embodiments, those skilled in the art, having benefitof this disclosure, will appreciate that various other embodiments maybe devised without departing from the scope of the present invention.Accordingly, the scope of the invention should be limited only by theattached claims.

The invention claimed is:
 1. An interlayer film for laminated glasscomprising: a first layer containing a thermoplastic resin; a secondlayer containing a thermoplastic resin; and a third layer containing athermoplastic resin, wherein the second layer is disposed on a firstsurface side of the first layer, wherein the third layer is disposed ona second surface side of the first layer that is opposite to the firstsurface, wherein the first layer has a glass transition temperature of10° C. or lower, wherein the interlayer film has an equivalent stiffnessof 2.4 MPa or greater at 25° C., and wherein, provided that a thicknessof the interlayer film for laminated glass is T, a thickness of thefirst layer is 0.128 T or greater and 0.4 T or less.
 2. The interlayerfilm for laminated glass according to claim 1, wherein a Young's modulusof the first layer at 25° C. is 0.4 MPa to 6 MPa.
 3. The interlayer filmfor laminated glass according to claim 1, wherein a glass transitiontemperature of the first layer is 5° C. or lower.
 4. The interlayer filmfor laminated glass according to claim 1, wherein the first layerfurther contains silica particles, and wherein a content of the silicaparticles in the first layer is 10 parts by weight to 64 parts by weightwith respect to 100 parts by weight of the thermoplastic resin in thefirst layer.
 5. The interlayer film for laminated glass according toclaim 1, wherein a Young's modulus of the second layer at 25° C. is 3MPa to 700 MPa.
 6. The interlayer film for laminated glass according toclaim 1, wherein the thermoplastic resin in the first layer is apolyvinyl acetal resin, and wherein the thermoplastic resin in thesecond layer is a polyvinyl acetal resin.
 7. The interlayer film forlaminated glass according to claim 6, wherein a concentration ofhydroxyl groups of the polyvinyl acetal resin in the first layer islower than a concentration of hydroxyl groups of the polyvinyl acetalresin in the second layer.
 8. The interlayer film for laminated glassaccording to claim 1, wherein the glass transition temperature of thefirst layer is lower than a glass transition temperature of the secondlayer.
 9. The interlayer film for laminated glass according to claim 8,wherein an absolute value of a difference between the glass transitiontemperature of the first layer and the glass transition temperature ofthe second layer is 30° C. or higher.
 10. The interlayer film forlaminated glass according to claim 1, wherein each of the first layer,the second layer, and the third layer contains a plasticizer.
 11. Theinterlayer film for laminated glass according to claim 1, wherein whenlaminated glass is obtained by interposing the interlayer film forlaminated glass between two sheets of green glass having a thickness of2 mm based on JIS R3208, a visible light transmittance of the obtainedlaminated glass is 70% or greater.
 12. The interlayer film for laminatedglass according to claim 1, wherein the interlayer film is used with afirst glass plate with a thickness of equal to or less than 1 mm and isarranged between the first glass plate and a second glass plate forobtaining laminated glass.
 13. A laminated glass comprising: a firstlamination glass member; a second lamination glass member; and theinterlayer film for laminated glass according to claim 1, wherein theinterlayer film for laminated glass is disposed between the firstlamination glass member and the second lamination glass member.
 14. Thelaminated glass according to claim 13, wherein the first laminationglass member is a first glass plate, and a thickness of the first glassplate is 1 mm or less.
 15. The interlayer film for laminated glassaccording to claim 1, wherein a Young's modulus of the second layer at25° C. is 25 MPa or greater.
 16. The interlayer film for laminated glassaccording to claim 1, wherein a Young's modulus of the third layer at25° C. is 25 MPa or greater.
 17. The interlayer film for laminated glassaccording to claim 1, wherein the interlayer film has an equivalentstiffness of 5 MPa or greater at 25° C.
 18. The interlayer film forlaminated glass according to claim 5, wherein a Young's modulus of thethird layer at 25° C. is 3 MPa to 700 MPa.
 19. The interlayer film forlaminated glass according to claim 8, wherein the glass transitiontemperature of the first layer is lower than a glass transitiontemperature of the third layer.
 20. The interlayer film for laminatedglass according to claim 19, wherein an absolute value of a differencebetween the glass transition temperature of the first layer and theglass transition temperature of the third layer is 30° C. or higher.